iPad keeps dinging when trying to connect to iTunes

I cannot connect my iPad to my MacBook Pro (Mid2105). The iPad keeps dinging and does not stay connected. I have tried more than 6 different factory and non-factory cables, tried all USB ports, tried rebooting, tried airplane mode, done hard resets etc etc etc. I have tried almost every other solution on the replies posted since 2016 where the same concern were noted. I have sufficient memory available on both devises and am at a loss. The MacBook Pro is running Sierra. MacBook iTunes is most recent version. iPad Air is running version 12.4.6. This iPad had been backed up to this Mac in the past. Any help would be appreciated. Thanks....and I really mean it.